Light-emitting device and manufacturing method thereof

ABSTRACT

When a hollow structure in which a light-emitting element is provided between a pair of substrates is used in order to prevent oxygen or moisture from reaching the light-emitting element, light leakage to an adjacent pixel easily occurs as compared to a structure in which a space between a pair of substrates is filled with a resin such as an adhesive. In order to reduce light leakage to an adjacent pixel in the hollow structure, a light-blocking spacer is formed over a partition to keep the distance between the pair of substrates uniform. The cross-sectional shape of the light-blocking spacer is a trapezoid having a lower side shorter than an upper side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting device in which alayer including an organic compound serves as a light-emitting layer anda method for manufacturing the light-emitting device.

2. Description of the Related Art

A light-emitting element containing an organic compound as a luminousbody, which has features such as thinness, lightness, high-speedresponse, and DC drive at a low voltage, is expected to be applied to anext-generation flat panel display or a next-generation lighting device.

A light-emitting mechanism of a light-emitting element is as follows: avoltage is applied between a pair of electrodes where a layer containingan organic compound is interposed, electrons injected from a cathode andholes injected from an anode are recombined with each other at anemitting center of the layer containing an organic compound (alsoreferred to as an EL layer) to form molecular excitons, and themolecular excitons release energy in returning to a ground state to emitlight. Singlet excitation and triplet excitation are known as excitedstates, and light emission can probably be achieved through either ofthe excited states.

An EL layer has a structure typified by a stacked structure of ahole-transport layer, a light-emitting layer, and an electron-transportlayer. EL materials for forming EL layers are roughly classified intolow molecular (monomer) materials and high (polymer) molecularmaterials. An evaporation apparatus is used for film formation of thelow molecular material.

In addition, a light-emitting element including a cathode, an EL layer,and an anode is called an EL element. There are two types of the ELelements: a type where an EL layer is formed between two kinds of stripeelectrodes that are provided crosswise (simple matrix type); and a typewhere an EL layer is formed between pixel electrodes that are connectedto TFTs and arranged in matrix and counter electrodes (active matrixtype). However, when the pixel density is increased, the active matrixtype where each pixel (or each dot) is provided with a switch isconsidered to be advantageous because it can be driven at a lowervoltage.

An EL material forming an EL layer deteriorates very easily anddeteriorates by easily oxidizing or absorbing moisture under thepresence of oxygen or water. Therefore, there are problems in that theluminance of light emission and the lifetime of a light-emitting elementdecrease. Therefore, by covering of a light-emitting element with asealing can, enclosure of dry air inside the sealing can, and attachmentof a drying agent, oxygen or moisture is prevented from reaching thelight-emitting element.

Further, a structure in which a spacer is provided over an insulatinglayer serving as a partition covering the periphery of a pixel electrodelayer is disclosed in Patent Document 1.

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    2006-126817

SUMMARY OF THE INVENTION

A conventional active matrix light-emitting device includes alight-emitting element in which an electrode electrically connected to aTFT over a substrate is formed as an anode, a layer containing anorganic compound is formed over the anode, and a cathode is formed overthe layer containing an organic compound. In the conventional activematrix light-emitting device, light generated in the layer containing anorganic compound is extracted to the TFT side through the anode that isa transparent electrode (hereinafter, such a structure is referred to asa bottom emission structure).

However, in this structure, there is a problem in that an aperture ratiois limited because of arrangement of a TFT, a wiring, and the like in apixel portion when resolution is improved.

In view of the above, an active matrix light-emitting device including alight-emitting element having a structure in which an electrodeelectrically connected to a TFT over a substrate is formed as an anodeon the TFT side, a layer containing an organic compound is formed overthe anode, and a cathode that is a transparent electrode is formed overthe layer containing an organic compound (hereinafter, such a structureis referred to as a top emission structure) is manufactured.

In a top emission structure, the number of material layers through whichlight emitted from a layer containing an organic compound passes can bereduced as compared to a bottom emission structure, and thus, straylight between material layers having different refractive indices can besuppressed.

Further, when a hollow structure in which a light-emitting element isprovided between a pair of substrates is used in order to prevent oxygenor moisture from reaching the light-emitting element, light leakage toan adjacent pixel easily occurs as compared to a structure in which aspace between a pair of substrates is filled with a resin such as anadhesive. In particular, as the space between the pair of substratesbecomes larger, light leakage to an adjacent pixel is increased.

Further, as the size of a pixel or a gap between pixels is reduced forthe purpose of realizing high definition display, light leakage to anadjacent pixel easily occurs; thus, display quality of a light-emittingdevice might be degraded due to color mixing, color shift, and the likein display.

Therefore, an object of an embodiment of the present invention is toprovide a structure in which light leakage to an adjacent pixel isreduced.

Further, in the case of a hollow structure in which a light-emittingelement is provided between a pair of substrates, it is also an objectto provide a structure in which the distance between the pair ofsubstrates can be kept uniform when the distance between the pair ofsubstrates is greater than or equal to 2 μm, or even greater than orequal to 3 μm.

In order to reduce light leakage to an adjacent pixel, a light-blockingspacer is formed over a partition to keep a distance between a pair ofsubstrates uniform.

An embodiment of the present invention is a light-emitting deviceincluding a first substrate; a transistor over the first substrate; afirst electrode connected to the transistor; a layer containing anorganic compound over the first electrode; a second electrode over thelayer containing an organic compound; a partition covering a peripheryof the first electrode; a light-blocking spacer over the partition; asecond substrate fixed to the first substrate; and a black matrix and acoloring layer in contact with the second substrate. The black matrixoverlaps with the second electrode over the light-blocking spacer. Thecoloring layer overlaps with the first electrode.

The pair of substrates is attached to each other so that thelight-blocking spacer is arranged to overlap with the black matrixprovided between coloring layers (also referred to as color filters).Full color display is performed using three pixels of a red pixel, ablue pixel, and a green pixel with the use of three coloring layers.Light emitted from a light-emitting element is white light. When thelight passes through one of the three coloring layers and the secondsubstrate, light having a desired color is obtained. A shape of a topsurface of the light-blocking spacer is a linear shape, a net-likeshape, a grid shape, or a linear shape having a branched protrudingportion.

A material which absorbs light and has a light-blocking property is usedfor the light-blocking spacer. For example, a black organic resin can beused, which can be formed by mixing a black resin of a pigment material,carbon black, titanium black, or the like into a resin material such asphotosensitive or non-photosensitive polyimide. In the case where ablack resin is used, the thickness thereof is greater than or equal to 1μm and less than or equal to 5 μm, and the resistivity thereof is higherthan or equal to 1×10⁵ Ωcm. The light-blocking spacer can absorb whitelight emitted from a light-emitting element obliquely with respect to aflat surface of the substrate and prevent light leakage in which lightpasses through a coloring layer of an adjacent pixel. Accordingly, thelight-blocking spacer can suppress reduction of chromaticity due tolight leakage.

Further, a cross-sectional shape of the light-blocking spacer is atrapezoid having a lower side shorter than an upper side. Specifically,a side surface of the light-blocking spacer forms an angle θ of greaterthan or equal to 90° with the flat surface of the substrate. When thecross section has such a shape, a first part of the layer containing anorganic compound, which is formed on the side surface of thelight-blocking spacer, is thinner than a second part of the layercontaining an organic compound in a light-emitting region (a regionoverlapping with the first electrode) to have high resistance;accordingly, current is prevented from flowing into an adjacent pixel.Particularly in the case where a layer having high conductivity isprovided as one of layers included in the layer containing an organiccompound, when part of the layer having high conductivity, which isformed on the side surface of the light-blocking spacer, is thin,current does not easily flow into an adjacent pixel, which is effective.Note that the first part of the layer containing an organic compound,which is formed on the side surface of the light-blocking spacer, is notnecessarily thin; the layer containing an organic compound may bedivided on the side surface of the light-blocking spacer. In the casewhere the layer containing an organic compound is divided, currentflowing into an adjacent pixel through the layer containing an organiccompound as a current path can be prevented.

Further, the layer containing an organic compound and the secondelectrode are formed over a top surface of the light-blocking spacer.Moreover, the pair of substrates is fixed to each other so that theblack matrix is arranged to be in contact with and overlap with thesecond electrode over the light-blocking spacer.

The black matrix and the coloring layer may be covered with a protectivelayer formed using an inorganic material such as silicon oxide so thatthe reliability of the light-emitting element is prevented fromdecreasing due to degasification of the black matrix and the coloringlayer. In this case, the second electrode is not in contact with theblack matrix and the protective layer is provided between the secondelectrode and the black matrix.

Further, a space between the first substrate and the second substrate isa reduced-pressure space, or is filled with an inert gas. When anitrogen gas which hardly contains moisture is used as an inert gasfilling the space between the pair of substrates, the reliability of thelight-emitting element can be increased.

A transparent substrate, typically a glass substrate is used as each ofthe first substrate and the second substrate, and the substrates arefixed to each other with the use of a sealant or glass with a lowmelting point, referred to as frit glass. In the case where frit glassis used, a pattern of a closed curve is formed with the use of the fritglass along an edge of one of the glass substrates, baking is performedat approximately 450° C., the pattern is pressed against the other ofglass substrates, and the pattern and the other of the glass substratesare welded together by laser welding; thus, a highly airtight glasssealed body is formed. Note that in the case where a pattern of a fritglass is formed over the second substrate, heating by laser or a lamp isperformed on only a region where the pattern is formed since the fitglass is baked after the black matrix and the coloring layer are formed.

Further, the first electrode is electrically connected to thetransistor. Moreover, a plurality of transistors is included in onepixel.

The transistor includes a semiconductor layer as an active layer. Asemiconductor film containing silicon as its main component, asemiconductor film containing an organic material as its main component,or a semiconductor film containing a metal oxide as its main componentcan be used as the semiconductor layer. As for the semiconductor filmcontaining silicon as its main component, an amorphous semiconductorfilm, a semiconductor film having a crystal structure, a film of acompound semiconductor having an amorphous structure, or the like can beused; specifically, amorphous silicon, microcrystalline silicon,polycrystalline silicon, single crystal silicon, or the like can beused. Further, for the semiconductor film containing a metal oxide asits main component, zinc oxide (ZnO), an oxide of zinc, gallium, andindium (In—Ga—Zn—O), an oxide of zinc, tin, and indium (In—Sn—Zn—O), orthe like can be used.

Alternatively, a transistor which is formed using a substrate of asemiconductor such as silicon or an SOI substrate can be used.

A black matrix, a light-blocking spacer, and a partition overlap withone another, whereby a panel structure in which a space between a pairof substrates can be kept uniform can be provided when the space betweenthe pair of substrates is greater than or equal to 2 μm or even greaterthan or equal to 3 μm. Further, for a display device including alight-emitting element, a panel structure in which light leakage to anadjacent pixel is reduced can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are a cross-sectional view and a top view illustratingan embodiment of the present invention;

FIGS. 2A and 2B are each an example of a top view illustrating anembodiment of the present invention;

FIG. 3 is an example of a top view illustrating an embodiment of thepresent invention;

FIG. 4 is an example of a structure of a light-emitting elementaccording to an embodiment of the present invention;

FIGS. 5A and 5B are photographs of a cross section of a spacer and FIG.5C is a schematic view thereof; and

FIGS. 6A to 6D each illustrate an example of an electronic deviceaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. However, the presentinvention is not limited to the description below, and it is easilyunderstood by those skilled in the art that modes and details disclosedherein can be modified in various ways without departing from the spiritand the scope of the present invention. Therefore, the present inventionis not construed as being limited to description of the embodiments.

Embodiment 1

An example of an active matrix light-emitting device will be describedwith reference to FIGS. 1A and 1B. Note that FIG. 1B is a plan view of alight-emitting device and FIG. 1A is a cross-sectional view taken alongdashed line A-A′ in FIG. 1B.

The active matrix light-emitting device of this embodiment includes apixel portion 802 provided over a glass substrate 801, a driver circuitportion (a source line driver circuit) 803, and a driver circuit portion(a gate line driver circuit) 804. The pixel portion 802, the drivercircuit portion 803, and the driver circuit portion 804 are sealed in aspace surrounded by a fixing portion 805, the glass substrate 801, and aglass substrate 806. In the glass substrate 806, a depression portion(also referred to as a drilled hole) is formed in a region other than aregion overlapping with the pixel portion 802, and a desiccant 823 isprovided for the depression portion for ensuring reliability of thelight-emitting element.

Over the glass substrate 801, a lead wiring 807 for connecting anexternal input terminal through which a signal (e.g., a video signal, aclock signal, a start signal, a reset signal, or the like) or apotential from the outside is transmitted to the driver circuit portion803 and the driver circuit portion 804 is provided. Here, an example isdescribed in which an FPC 808 is provided as the external inputterminal. Note that although only an FPC is illustrated here, a printedwiring board (PWB) may be attached to the FPC. In this specification,the light-emitting device includes in its category the light-emittingdevice itself and the light-emitting device on which the FPC or the PWBis mounted.

Next, a cross-sectional structure of the active matrix light-emittingdevice is described with reference to FIG. 1A. Although the drivercircuit portion 803, the driver circuit portion 804, and the pixelportion 802 are formed over the glass substrate 801, the pixel portion802 and the driver circuit portion 803 which is the source line drivercircuit are illustrated in FIG. 1A.

An example is illustrated in which the driver circuit portion 803includes a CMOS circuit which is a combination of an n-channeltransistor 809 and a p-channel transistor 810. Note that a circuitincluded in the driver circuit portion can be aimed using various typesof circuits such as a CMOS circuit, a PMOS circuit, or an NMOS circuit.In this embodiment, a driver-integrated type in which a driver circuitand the pixel portion are formed over the same substrate is described;however, the present invention is not limited to this structure, and adriver circuit can be formed over a substrate that is different from thesubstrate over which a pixel portion is formed.

The pixel portion 802 includes a plurality of pixels each including aswitching transistor, a current control transistor 812, and an anode 813electrically connected to a wiring (a source electrode or a drainelectrode) of the current control transistor 812. A partition 814 isformed to cover an end portion of the anode 813. In this embodiment, thepartition 814 is formed using a positive photosensitive acrylic resin.Note that top-gate transistors are illustrated as the transistors suchas the switching transistor and the current control transistor 812;however, the structure of the transistors is not limited to the top-gatestructure. For example, a bottom-gate transistor such as an invertedstaggered transistor may be used.

A material of a semiconductor layer used for each of the transistors isnot particularly limited. The semiconductor layer is formed by a knownmethod. Here, a semiconductor film having a crystal structure is used,which is formed in such a manner that an amorphous silicon film isformed by a known method (e.g., a sputtering method, an LPCVD method, ora plasma CVD method), and then the amorphous silicon film iscrystallized by known crystallization treatment (e.g., a lasercrystallization method, a thermal crystallization method, or a thermalcrystallization method using a catalyst such as nickel). The pluralityof semiconductor layers serves as active layers of transistors to beformed later. It is preferable to use a semiconductor film having acrystal structure for an active layer of a transistor in order torealize high-speed driving of a driver circuit.

A light-emitting element 817 includes the anode 813, a layer containingan organic compound (EL layer) 815, and a cathode 816. The structure,the material, and the like of the light-emitting element are asdescribed above. Although not illustrated, the cathode 816 iselectrically connected to the FPC 808 which is an external inputterminal.

The partition 814 is provided at the end portion of the anode 813 tocover the peripheral portion of the anode 813. In addition, in orderthat the cathode 816 formed over the partition 814 favorably covers thepartition 814, the partition 814 is preferably formed so as to have acurved surface with curvature at an upper end portion or a lower endportion. For example, it is preferable that the upper end portion or thelower end portion of the partition 814 have a curved surface with aradius of curvature (0.2 μm to 3 μm). The partition 814 can be formedusing an organic compound such as a negative photosensitive resin whichbecomes insoluble in an etchant by light or a positive photosensitiveresin which becomes soluble in an etchant by light, or an inorganiccompound such as silicon oxide or silicon oxynitride.

A light-blocking 819 is provided over the partition 814. Thelight-blocking spacer 819 is formed using a material which absorbs lightand has a light-blocking property. For example, a black organic resin isused. The light-blocking spacer 819 absorbs light emitted from thelight-emitting element 817 obliquely to the flat surface of thesubstrate and can prevent light leakage in which light passes through acoloring layer of an adjacent pixel.

FIG. 2A is an example of a top view showing shapes of top surfaces ofthe light-blocking spacers 819 and a positional relation between thelight-blocking spacers 819 and the anodes 813. Note that in FIG. 2A, twokinds of light-blocking spacers 819, which have different shapes of thetop surfaces, are illustrated. The light-blocking spacers 819 are eachprovided between pixels. FIG. 2A illustrates the light-blocking spacer819 which has a linear shape with a width of 5 μm to 10 μm and thelight-blocking spacer 819 which has a linear shape with a width of 5 μmto 10 μm and includes a branched portion. The branched portion of thelight-blocking spacer 819 has a function of supporting a long and narrowspacer with a width of approximately 5 μm.

Further, the shape of the top surface of the light-blocking spacer 819is not limited to the one illustrated in FIG. 2A. For example, thelight-blocking spacers 819 which have liner shapes having differentlengths may be arranged as illustrated in FIG. 2B. Further, asillustrated in FIG. 3, one light-blocking spacer 819, which has anet-like shape, may be provided. Note that in FIG. 3, voltage might dropsignificantly due to an increase of resistance of the cathode 816;therefore, it is preferable that a region where the spacer 819 is notprovided be formed around a corner of a pixel, as illustrated in FIGS.2A and 2B.

Further, as illustrated in FIG. 1A, the cross-sectional shape of thelight-blocking spacer 819 is a trapezoid having a lower side shorterthan an upper side. Specifically, a side surface of the light-blockingspacer 819 forms an angle θ of greater than or equal to 90° with theflat surface of the glass substrate 801. With such a cross-sectionalshape, part of the layer 815 containing an organic compound, which isformed on the side surface of the light-blocking spacer 819, can bethinner than part of the layer 815 containing an organic compound in alight-emitting region (a region overlapping with the anode 813) to havehigh resistance; thus, current can be prevented from flowing into anadjacent pixel. A region having high resistance can be formed on theside surface of the light-blocking spacer 819 or between adjacentspacers; thus, in the case where a cathode and an anode are shortcircuited for some reason, a short circuit of adjacent pixels caused dueto heat generation, which might cause damage spread, can be prevented.

Further, the layer 815 containing an organic compound and the cathode816 are formed over the top surface of the light-blocking spacer 819.The pair of substrates is fixed by the fixing portion 805 so that theblack matrix 822 is in contact with and overlaps with the cathode 816over the light-blocking spacer 819. The fixing portion 805 may be formedusing a sealant of an ultraviolet curable resin, a thermosetting resin,or the like, or may be formed in such a manner that a fit glass iswelded by laser.

In this embodiment, an acrylic photocurable resin or an acrylicthermosetting resin is used as the sealant. After a seal pattern isformed over the second substrate, the pair of substrates is attached toeach other under a reduced pressure, and ultraviolet irradiation or heattreatment is performed; thus, the sealant is cured to form the fixingportion 805. This sealant is formed into a closed loop and surrounds thepixel portion 802. As the sealant, a sealant containing filler (with adiameter of 1 μm to 5 μm) and having a viscosity of 40 Pa·s to 400 Pa·sis used.

Although the cross-sectional view of FIG. 1A illustrates only onelight-emitting element 817, a plurality of light-emitting elements isarranged in matrix in the pixel portion 802. For example, a plurality oflight-emitting elements each emitting white light is provided in thepixel portion 802 and three kinds of coloring layers 821 (R, B) eachoverlapping with the light-emitting element are provided; thus, alight-emitting device capable of full color display can be provided. Thelight-emitting device has a top emission structure; light is emittedfrom the light-emitting element 817 in the direction indicated by anarrow 820 in FIG. 1A.

The light-emitting element 817 is formed in a closed space 818 that issurrounded by the glass substrate 801, the glass substrate 806, and thefixing portion 805. The closed space 818 is filled with an inert gas inwhich moisture is sufficiently reduced.

As described above, the active matrix light-emitting device according toan embodiment of the present invention can be obtained. Such alight-emitting device has a long lifetime.

Embodiment 2

In this embodiment, a specific example of a stack of the layer 815containing an organic compound described in Embodiment 1 will bedescribed with reference to FIG. 4.

Over a first electrode layer 103, a hole-injection layer 141, a firstlight-emitting unit 142, an intermediate layer 143, a secondlight-emitting unit 144, an intermediate layer 145, a thirdlight-emitting unit 146, an electron-injection layer 147, and a secondelectrode layer 107 are stacked in this order. For the first electrodelayer 103, an element belonging to Group 1 or 2 of the periodic table,that is, an alkali metal such as lithium (Li) or cesium (Cs), analkaline earth metal such as calcium (Ca) or strontium (Sr), ormagnesium (Mg) can be used. Further, an alloy containing an alkalimetal, an alkaline earth metal, or magnesium (e.g., MgAg or AlLi) can beused. Moreover, a rare earth metal such as europium (Eu) or ytterbium(Yb), or an alloy containing a rare earth metal can also be used.Alternatively, a variety of conductive materials such as Al, Ag, and ITOcan be used for the first electrode layer 103. A metal, an alloy, aconductive compound, or a mixture thereof is preferably used for thesecond electrode layer 107. Specifically, indium tin oxide (ITO), indiumtin oxide containing silicon or silicon oxide, indium zinc oxide, indiumoxide containing tungsten oxide and zinc oxide (IWZO), or the like canbe given. In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten(W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper(Cu), palladium (Pd), a nitride of a metal material (e.g., titaniumnitride), or the like can be used for the second electrode layer 107.

Each of the first light-emitting unit 142, the second light-emittingunit 144, and the third light-emitting unit 146 includes at least alight-emitting layer containing a light-emitting substance, and may havea structure in which a layer other than the light-emitting layer and thelight-emitting layer are stacked. Examples of the layer other than thelight-emitting layer include a layer containing a substance having ahigh hole-injection property, a layer containing a substance having ahigh hole-transport property, a layer containing a substance having apoor hole-transport property (a substance which blocks holes), a layercontaining a substance having a high electron-transport property, alayer containing a substance having a high electron-injection property,a layer containing a substance having a bipolar property (a substancehaving a high electron-transport property and a high hole-transportproperty), and the like. As a light-emitting substance, for example, afluorescent compound which emits fluorescence or a phosphorescentcompound which emits phosphorescence can be used. The use ofphosphorescent compounds for emission of all of red (R) light, green (G)light, and blue (B) light makes it possible to obtain high luminousefficiency.

FIG. 4 illustrates a stacked element in which three units, which are thefirst light-emitting unit 142, the second light-emitting unit 144, andthe third light-emitting unit 146, are stacked. In the case of thestacked element, a color of light emitted from the first light-emittingunit 142, a color of light emitted from the second light-emitting unit144, and a color of light emitted from the third light-emitting unit 146are complementary colors to one another; thus, white light emission canbe extracted to the outside. Note that also in the case where the firstlight-emitting unit 142, the second light-emitting unit 144, and thethird light-emitting unit 146 each include a plurality of light-emittinglayers which emits light of complementary colors to one another, whitelight emission can be obtained. As a complementary relation, blue andyellow, blue green and red, and the like can be given.

The hole-injection layer 141 is a layer containing a substance having ahigh hole-injection property. As the substance having a highhole-injection property, for example, molybdenum oxide, vanadium oxide,ruthenium oxide, tungsten oxide, manganese oxide, or the like can beused. Besides the above, phthalocyanine based compounds such asphthalocyanine (H₂Pc) and copper phthalocyanine (CuPc) can be used.

For the hole-injection layer 141, a composite material in which anacceptor substance is added to an organic compound having a highhole-transport property is preferably used. Such a composite materialcan be formed by co-evaporation of a substance having a highhole-transport property and an acceptor substance. In this embodiment, acomposite material of molybdenum oxide and an aromatic amine compound isused for the hole-injection layer 141.

The intermediate layer 143 and the intermediate layer 145 are eachformed to include at least a charge generation region, and may have astacked structure of the charge generation region and a layer other thanthe charge generation region. The charge generation region is notlimited to a structure in which a substance having a high hole-transportproperty and an acceptor substance are contained in the same film, andmay have a structure in which a layer containing a substance having ahigh hole-transport property and a layer containing an acceptorsubstance are stacked. Note that the acceptor substance is preferablyadded to the charge generation region so that the mass ratio of theacceptor substance to the substance having a high hole-transportproperty is from 0.1:1 to 4.0:1. As the acceptor substance that is usedfor the charge production region, a transition metal oxide can be given.Specifically, molybdenum oxide is particularly preferable. Note thatmolybdenum oxide has a low hygroscopic property. As the substance havinga high hole-transport property used for the charge generation region,any of a variety of organic compounds such as an aromatic aminecompound, a carbazole derivative, an aromatic hydrocarbon, and a highmolecular compound (such as an oligomer, a dendrimer, or a polymer) canbe used. Specifically, a substance having a hole mobility of 10⁻⁶ cm²/Vsor higher is preferably used. However, a substance other than theabove-described materials may also be used as long as the substance hasa higher hole-transport property than an electron-transport property.

The electron-injection layer 147 is a layer containing a substancehaving a high electron-injection property. As the substance having ahigh electron-injection property, the following can be given: an alkalimetal, an alkaline earth metal, and a compound thereof, such as lithium(Li), cesium (Cs), calcium (Ca), lithium fluoride (LiF), cesium fluoride(CsF), and calcium fluoride (CaF₂). Alternatively, a layer containing asubstance having an electron-transport property and an alkali metal, analkaline earth metal, magnesium (Mg), or a compound thereof (e.g., Alqcontaining magnesium (Mg)) can be used. In this embodiment, a compositematerial of molybdenum oxide and an aromatic amine compound is used forthe electron-injection layer 147 so that damage due to sputtering information of the second electrode layer 107 can be reduced.

When a charge generation layer is provided as one layer included in thelayer 815 containing an organic compound as illustrated in FIG. 4, anelement can have both high luminance and a long lifetime while thecurrent density is kept low. In addition, the voltage drop due toresistance of the electrode material can be reduced, whereby uniformlight emission in a large area is possible.

Since the light-emitting element in this embodiment is a top-emissionlight-emitting element, an optical path adjusting film may be formedover the first electrode layer 103 so that light emitted from the layer815 containing an organic compound and light reflected by the firstelectrode layer 103 interfere with each other and light having aspecific wavelength is strengthened. The optical path adjusting film ispreferably formed with a film which has a light-transmitting propertyand does not affect carrier injection to the layer 815 containing anorganic compound.

Since the intermediate layer 143 and the intermediate layer 145 havehigh conductivity, it is important to provide the light-blocking spacer819 over the partition 814 as illustrated in FIG. 1A. Since theintermediate layer 143 and the intermediate layer 145 are provided overthe partition which is provided between pixels, current might flow intoan adjacent pixel and an unintended pixel might emit light unless thelight-blocking spacer 819 is provided, although it depends on a distancebetween the pixels.

The cross-sectional shape of the light-blocking spacer 819 is such thatthe side surface of the light-blocking spacer 819 forms an angle θ ofgreater than or equal to 90° with the flat surface of the substrate.With the light-blocking spacer 819 having such a cross-sectional shape,the layer 815 containing an organic compound formed on the side surfaceof the light-blocking spacer 819 can be made thin; accordingly, theintermediate layer 143 and the intermediate layer 145 can be made thinand the resistance of the layer 815 containing an organic compound canbe increased.

An actual state where a spacer is formed and a layer containing anorganic compound is evaporated is described below. FIG. 5A is across-sectional TEM image in which a layer containing an organiccompound is formed over a spacer in which a side surface thereof formsan angle θ of approximately 100° with a flat surface of a substrate.

In FIG. 5A, the height of the spacer is approximately 1.8 μm and thetotal thickness of the layer containing an organic compound isapproximately 210 nm. A first electrode is a stack of a Ti film having athickness of 50 nm, an Al film having a thickness of 200 nm, and a Tifilm having a thickness of 3 nm. The thickness of an ITO film which is asecond electrode is approximately 70 nm.

FIG. 5B is an enlarged TEM image of part of FIG. 5A. FIG. 5C is aschematic view of FIG. 5B. As shown in FIGS. 5B and 5C, a thin layer 203containing an organic compound formed on is formed also on a sidesurface of a spacer 202, and it can be confirmed that the thickness ofpart of the layer 203 containing an organic compound on the side surfaceof the spacer is reduced to approximately 40 nm, which is approximatelyone fifth of part of the layer 203 having a thickness of approximately210 nm over the spacer. Further, the thickness of the ITO film which isa second electrode 204 on the side surface of the spacer 202 is alsoreduced.

According to this result, when a side surface of a spacer forms an angleθ of greater than or equal to 90° with a flat surface of a substrate,part of the layer 203 containing an organic compound, which is formed onthe side surface of the spacer, is made thin and part of theintermediate layers 143 and 145 having high conductivity can beaccordingly made thin to have high resistance; thus, light emission froman adjacent pixel can be prevented. Note that the spacer in FIGS. 5A and5B is formed using an acrylic resin, which does not have alight-blocking property. The spacer obtains a light-blocking property bydispersion a material which does not transmit light or absorbs light;thus, light leakage to an adjacent pixel can be suppressed. As amaterial of a light-blocking spacer, a material in which a materialwhich does not transmit light or absorbs light is dispersed in a resinsuch as an epoxy resin, an acrylic resin, an acrylic epoxy resin, asiloxane polymer-based resin, or a polyimide resin can be used. As thematerial which is dispersed in a resin, carbon black, titanium oxide,titanium oxynitride, or the like can be used. The light-blocking spaceris preferably has high resistivity; specifically, a material having aresistivity of 1×10⁵ Ωcm is used. In the stacked structure illustratedin FIG. 4, a composite material of molybdenum oxide and an aromaticamine compound, which is used for the hole-injection layer 141, has aresistivity of 1×10⁵ Ωcm; therefore, the light-blocking spacer is formedusing a material having resistivity higher than the composite material.

Note that this embodiment can be freely combined with Embodiment 1.

Embodiment 3

In this embodiment, specific examples of electronic devices each ofwhich is manufactured using the light-emitting device described in theabove embodiments will be described with reference to FIGS. 6A to 6D.

Examples of electronic devices to which the present invention can beapplied include a television set (also referred to as a television or atelevision receiver), a monitor of a computer or the like, a digitalcamera, a digital video camera, a digital photo frame, a mobile phone, aportable game machine, a portable information terminal, an audioreproducing device, a game machine (e.g., a pachinko machine or a slotmachine), a housing of a game machine, and the like. Specific examplesof these electronic devices are shown in FIGS. 6A to 6D.

FIG. 6A illustrates a table 9000 having a display portion. In the table9000, a display portion 9003 is incorporated into a housing 9001. Alight-emitting device manufactured according to an embodiment of thepresent invention can be used for the display portion 9003, and an imagecan be displayed on the display portion 9003. Note that the housing 9001is supported by four leg portions 9002. Further, a power cord 9005 forsupplying power is provided for the housing 9001.

The display portion 9003 has a touch input function. When a displaybutton 9004 displayed on the display portion 9003 of the table 9000 istouched by a finger or the like, a screen can be operated or data can beinput. Further, the screen of the display portion 9003 can be placedperpendicular to a floor with a hinge provided for the housing 9001;thus, the table 9000 can also be used as a television device. When atelevision device having a large screen is set in a small room, an openspace is reduced; however, when a display portion is incorporated in atable, a space in the room can be efficiently used.

The light-emitting device including the light-blocking spacer, which isdescribed in the above embodiments, is employed, whereby color mixing,color shift, or the like in display does not easily occur; therefore,when the light-emitting device is used for the display portion 9003, thedisplay portion 9003 can have display quality higher than a conventionaldisplay portion. In addition, the pair of substrates is supported by thelight-blocking spacer, so that the light-emitting device is extremelyresistant to external force such as impact, distortion, or the like.Thus, the light-emitting device can be favorably used for the tableillustrated in FIG. 6A.

FIG. 6B illustrates a television set 9100. In the television set 9100, adisplay portion 9103 is incorporated in a housing 9101. A light-emittingdevice manufactured according to an embodiment of the present inventioncan be used in the display portion 9103, and an image can be displayedon the display portion 9103. Note that the housing 9101 is supported bya stand 9105 here.

The television set 9100 can be operated with an operation switchprovided for the housing 9101 or a separate remote controller 9110.Channels and volume can be controlled with an operation key 9109 of theremote controller 9110 so that an image displayed on the display portion9103 can be controlled. Furthermore, the remote controller 9110 may beprovided with a display portion 9107 for displaying data output from theremote controller 9110.

The television set 9100 illustrated in FIG. 6B is provided with areceiver, a modem, and the like. With the receiver, the television set9100 can receive a general television broadcast. Further, when thetelevision set 9100 is connected to a communication network by wired orwireless connection via the modem, one-way (from a transmitter to areceiver) or two-way (between a transmitter and a receiver or betweenreceivers) data communication can be performed.

The light-emitting device including the light-blocking spacer, which isdescribed in the above embodiments, is employed, whereby color mixing,color shift, or the like in display does not easily occur; therefore,when the light-emitting device is used for the display portion 9103 ofthe television set, the television set can have display quality higherthan a conventional television set.

FIG. 6C illustrates a computer which includes a main body 9201, ahousing 9202, a display portion 9203, a keyboard 9204, an externalconnection port 9205, a pointing device 9206, and the like. The computeris manufactured using light-emitting device manufactured according to anembodiment of the present invention for the display portion 9203.

The light-emitting device including the light-blocking spacer, which isdescribed in the above embodiments, is employed, whereby color mixing,color shift, or the like in display does not easily occur; therefore,when the light-emitting device is used for the display portion 9203 ofthe computer, the display portion can have display quality higher than aconventional display portion.

FIG. 6D illustrates an example of a mobile phone. A mobile phone 9500 isprovided with a display portion 9502 incorporated in a housing 9501, anoperation button 9503, an external connection port 9504, a speaker 9505,a microphone 9506, and the like. Note that the mobile phone 9500 ismanufactured using a light-emitting device manufactured according to anembodiment of the present invention for the display portion 9502.

Users can input data, make a call, or text a message by touching thedisplay portion 9502 of the mobile phone 9500 illustrated in FIG. 6Dwith their fingers or the like.

There are mainly three screen modes for the display portion 9502. Thefirst mode is a display mode mainly for displaying images. The secondmode is an input mode mainly for inputting data such as text. The thirdmode is a display-and-input mode in which two modes of the display modeand the input mode are combined.

For example, in the case of making a call or text messaging, a textinput mode mainly for inputting text is selected for the display portion9502 so that characters displayed on a screen can be input. In thiscase, it is preferable to display a keyboard or number buttons on almostthe entire screen of the display portion 9502.

By providing a detection device which includes a sensor for detectinginclination, such as a gyroscope or an acceleration sensor, inside themobile phone 9500, the direction of the mobile phone 9500 (whether themobile phone 9500 is placed horizontally or vertically for a landscapemode or a portrait mode) is determined so that display on the screen ofthe display portion 9502 can be automatically switched.

In addition, the screen mode is switched by touching the display portion9502 or operating the operation button 9503 of the housing 9501.Alternatively, the screen modes can be switched depending on kinds ofimages displayed on the display portion 9502. For example, when a signalof an image displayed on the display portion is a signal of moving imagedata, the screen mode is switched to the display mode. When the signalis a signal of text data, the screen mode is switched to the input mode.

Moreover, in the input mode, when input by touching the display portion9502 is not performed within a specified period of time while a signaldetected by an optical sensor in the display portion 9502 is detected,the screen mode may be controlled so as to be switched from the inputmode to the display mode.

The display portion 9502 can also function as an image sensor. Forexample, an image of a palm print, a fingerprint, or the like is takenby touching the display portion 9502 with the palm or the finger,whereby personal authentication can be performed. Further, by providinga backlight or a sensing light source emitting near-infrared light inthe display portion, an image of a finger vein, a palm vein, or the likecan be taken.

The light-emitting device including the light-blocking spacer, which isdescribed in the above embodiments, is employed, whereby color mixing,color shift, or the like in display does not easily occur; therefore,when the light-emitting device is used for the display portion 9502 ofthe mobile phone, the mobile phone can have display quality higher thana conventional mobile phone. In addition, the pair of substrates issupported by the light-blocking spacer, so that the light-emittingdevice is extremely resistant to external force such as impact,distortion, or the like. Thus, the light-emitting device can befavorably used for the mobile phone illustrated in FIG. 6D.

The structures and methods described in this embodiment can be combinedas appropriate with any of the structures and methods described in theother embodiments.

This application is based on Japanese Patent Application serial no.2011-099992 filed with Japan Patent Office on Apr. 27, 2011, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A light-emitting device comprising: a firstsubstrate; a transistor over a first surface of the first substrate; aninsulating film over the transistor; a first electrode on the insulatingfilm, the first electrode electrically connected to the transistor; alight-emitting layer over the first electrode; a second electrode overthe light-emitting layer; a partition on the insulating film, thepartition covering a periphery of the first electrode; a light-blockingspacer on the partition, the light-blocking spacer being covered withthe light-emitting layer and the second electrode; a second substratefixed to the first substrate; and first and second black matrixes with acoloring layer positioned therebetween which are in contact with thesecond substrate, wherein a cross-sectional shape of the light-blockingspacer is a trapezoid having a lower side shorter than an upper side,wherein the first black matrix covers the light-blocking spacer with thesecond electrode positioned therebetween, wherein the second blackmatrix overlaps with the transistor and is apart from the secondelectrode, and wherein the coloring layer overlaps with the firstelectrode.
 2. The light-emitting device according to claim 1, wherein aspace between the first substrate and the second substrate is areduced-pressure space.
 3. The light-emitting device according to claim1, wherein a space between the first substrate and the second substrateis filled with an inert gas.
 4. The light-emitting device according toclaim 1, wherein the first black matrix is in contact with the secondelectrode.
 5. The light-emitting device according to claim 1, whereinthe first and second black matrixes and the coloring layer are coveredwith a protective layer comprising an inorganic material, and whereinthe protective layer is in contact with the second electrode.
 6. Thelight-emitting device according to claim 1, wherein the light-blockingspacer comprises a black resin.
 7. The light-emitting device accordingto claim 1, wherein a side surface of the light-blocking spacer forms anangle of greater than 90° with the first surface of the first substrate.8. The light-emitting device according to claim 1, wherein a first partof the light-emitting layer, which is formed on a side surface of thelight-blocking spacer, is thinner than a second part of thelight-emitting layer in a region overlapping with the first electrode.9. The light-emitting device according to claim 1, wherein a shape of atop surface of the light-blocking spacer is a linear shape.
 10. Thelight-emitting device according to claim 1, wherein a shape of a topsurface of the light-blocking spacer is a net-like shape.
 11. Alight-emitting device comprising: a first substrate; an insulating filmover a first surface of the first substrate; a light-emitting elementcomprising a first electrode on the insulating film, a light-emittinglayer, and a second electrode; a partition over the insulating film, thepartition covering a periphery of the first electrode; a spacer havinglight-blocking property over the partition, the spacer being coveredwith the light-emitting layer and the second electrode; a secondsubstrate fixed to the first substrate; and a first black matrix and acoloring layer on a first surface of the second substrate, wherein across-sectional shape of the spacer is a trapezoid having a lower sideshorter than an upper side, wherein a first part of the light-emittinglayer, which is formed on a side surface of the spacer, is thinner thana second part of the light-emitting layer in a region overlapping withthe first electrode, wherein the first black matrix overlaps with thespacer, and wherein the coloring layer overlaps with the light-emittingelement.
 12. The light-emitting device according to claim 11, furthercomprising a transistor electrically connected to the light-emittingelement over the first surface of the first substrate.
 13. Thelight-emitting device according to claim 11, wherein a space between thefirst substrate and the second substrate is a reduced-pressure space.14. The light-emitting device according to claim 11, wherein a spacebetween the first substrate and the second substrate is filled with aninert gas.
 15. The light-emitting device according to claim 11, whereinthe first black matrix is in contact with the second electrode.
 16. Thelight-emitting device according to claim 11, wherein the first blackmatrix and the coloring layer are covered with a protective layercomprising an inorganic material over the first surface of the secondsubstrate, and wherein the protective layer is in contact with thesecond electrode.
 17. The light-emitting device according to claim 11,wherein the spacer comprises a black resin.
 18. The light-emittingdevice according to claim 11, wherein the side surface of the spacerforms an angle of greater than 90° with the first surface of the firstsubstrate.
 19. The light-emitting device according to claim 12, furthercomprising a second black matrix on the first surface of the secondsubstrate, the second black matrix being apart from the second electrodeand overlapping with the transistor.
 20. The light-emitting deviceaccording to claim 11, wherein a shape of a top surface of the spacer isa linear shape.
 21. The light-emitting device according to claim 11,wherein a shape of a top surface of the spacer is a net-like shape. 22.A light-emitting device comprising: a first substrate; a transistor overa first surface of the first substrate; an insulating film over thetransistor; a first electrode on the insulating film, the firstelectrode electrically connected to the transistor; a light-emittinglayer over the first electrode; a second electrode over thelight-emitting layer; a partition on the insulating film, the partitioncovering a periphery of the first electrode; a light-blocking spacerover the partition, the light-blocking spacer being covered with thelight-emitting layer and the second electrode; and a second substratefixed to the first substrate, wherein a cross-sectional shape of thelight-blocking spacer is a trapezoid having a lower side shorter than anupper side, and wherein a first part of the light-emitting layer, whichis formed on a side surface of the light-blocking spacer, is thinnerthan a second part of the light-emitting layer in a region overlappingwith the first electrode.
 23. The light-emitting device according toclaim 22, wherein a space between the first substrate and the secondsubstrate is a reduced-pressure space.
 24. The light-emitting deviceaccording to claim 22, wherein a space between the first substrate andthe second substrate is filled with an inert gas.
 25. The light-emittingdevice according to claim 22, further comprising: a first black matrixover the light-blocking spacer, the first black matrix being in contactwith the second electrode; and a second black matrix over thetransistor, the second black matrix being apart from the secondelectrode.
 26. The light-emitting device according to claim 22, whereinthe light-blocking spacer comprises a black resin.
 27. Thelight-emitting device according to claim 22, wherein the side surface ofthe light-blocking spacer forms an angle of greater than 90° with thefirst surface of the first substrate.
 28. The light-emitting deviceaccording to claim 22, wherein a top surface of the light-blockingspacer is in contact with the light-emitting layer and a bottom surfaceof the light-blocking spacer is in contact with the partition.
 29. Thelight-emitting device according to claim 22, wherein a shape of a topsurface of the light-blocking spacer is a linear shape.
 30. Thelight-emitting device according to claim 22, wherein a shape of a topsurface of the light-blocking spacer is a net-like shape.